Substrate processing apparatus

ABSTRACT

Described herein is a technique capable of acquiring, monitoring and recording the progress of the reaction between a substrate and a reactive gas contained in a process gas in a process chamber during the processing of the substrate. According to the technique, there is provided a substrate processing apparatus including: a process chamber accommodating a substrate; a process gas supply system configured to supply a process gas into the process chamber via a process gas supply pipe; an exhaust pipe configured to exhaust an inner atmosphere of the process chamber; a first gas concentration sensor configured to detect a first concentration of a reactive gas contained in the process gas in the process gas supply pipe; and a second gas concentration sensor configured to detect a second concentration of the reactive gas contained in an exhaust gas in the exhaust pipe.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This non-provisional U.S. patent application claims priority under 35U.S.C. § 119 of International Application No. PCT/JP2015/077502, filedon Sep. 29, 2015, in the WIPO, the entire contents of which are herebyincorporated by reference.

BACKGROUND 1. Field

The present disclosure relates to a substrate processing apparatus.

2. Description of the Related Art

It is becoming more difficult to control interference between transistordevices due to leakage currents as the devices in a Large ScaleIntegrated circuit (hereinafter referred to as LSI) are miniaturized.The devices in the LSI are separated by forming voids such as grooves orholes in a silicon substrate and depositing an insulator in the voids.For example, an oxide film such as a silicon oxide film (SiO film) maybe used as the insulator. The SiO film may be formed by oxidation of thesilicon substrate, a chemical vapor deposition (CVD) method or aSpin-On-Dielectric (SOD) method.

Recently, with the miniaturization of devices, the technology of fillingmicrostructures, especially filling deep or narrow voids with oxide, bythe CVD method has reached its limit. In order to overcome the limits, amethod of using an oxide having fluidity such as SOD (“SOD method”) tofill the voids has been introduced. In the SOD method, an insulatingcoating material containing an inorganic component or an organiccomponent called SOG (Spin-On-Glass) is used. The insulating coatingmaterial has been used in the manufacturing process of LSI before CVDoxide film was introduced. Since the manufacturing process of the LSIusing the insulating coating material only requires 0.35 μm to 1 μmprocesses, the insulating coating material may be modified by performingthe heat treatment at 400° C. under the nitrogen atmosphere. However,since latest manufacturing process of LSI such as DRAM (Dynamic RandomAccess Memory) and flash memory requires processes less than 50 nmprocesses, polysilazane (SiH₂NH) or PHPS (perhydropolysilazane) is usedinstead of SOG.

Polysilazane is a material obtained by catalytic reaction ofdichlorosilane or trichlorosilane with ammonia, for example. A thin filmmay be formed by applying polysilazane on a substrate using a spincoater. The thickness of the coating film depends on the molecularweight and the viscosity of the polysilazane and the number ofrevolutions of the spin coater.

Polysilazane contains impurities such as nitrogen from ammonia used inthe manufacturing process thereof. Therefore, it is necessary to removeimpurities from the coating film (polysilazane film) by subjecting thepolysilazane film to moisture and heat treatment after coating to obtaina dense oxide film. For example, moisture can be formed by reactinghydrogen and oxygen in a heat processing furnace to add moisture to thepolysilazane film. The moisture permeates the polysilazane film and byheating the polysilazane film a dense oxide film is obtained. In case ofSTI (Shallow Trench Isolation), the maximum temperature of the heattreatment may be, for example, about 1,000° C.

While polysilazane has been widely used in LSI processes, it isnecessary to reduce the thermal load of the transistor elements in orderto prevent excessive diffusion of impurities such as boron, arsenic andphosphorus implanted in the transistor elements, to prevent theaggregation of metal silicide for electrode, to prevent the fluctuationof the performance of the work-function metal material for gateelectrode, and to secure the number of read/write operations of thememory element. If moisture can be added efficiently, the thermal loadcan be easily reduced in the heat treatment performed after addingmoisture.

Instead of filling the voids with insulator via the CVD method, thevoids may be filled with insulator via a flowable CVD method.

In a substrate processing using a process gas, for example, in a processfor obtaining a dense oxide film by modifying a polysilazane film coatedby SOD or insulating material filled by a flowable CVD method, it isnecessary to accurately acquire, monitor, and record the status of thesubstrate processing such as the progress of the substrate processing.

SUMMARY

Described herein is a technique capable of acquiring, monitoring andrecording the progress of the reaction between a substrate and areactive gas contained in a process gas in a process chamber during theprocessing of the substrate.

According to one aspect of the technique described herein, there isprovided a substrate processing apparatus including: a process chamberaccommodating a substrate; a process gas supply system configured tosupply a process gas into the process chamber via a process gas supplypipe; an exhaust pipe configured to exhaust an inner atmosphere of theprocess chamber; a first gas concentration sensor configured to detect afirst concentration of a reactive gas contained in the process gas inthe process gas supply pipe; a second gas concentration sensorconfigured to detect a second concentration of the reactive gascontained in an exhaust gas in the exhaust pipe; and a controllerconfigured to: (a) control the process gas supply system to supply theprocess gas to the substrate in the process chamber; (b) acquire thefirst concentration detected by the first gas concentration sensor andthe second concentration detected by the second gas concentration sensorat predetermined time interval, and calculate and record in a memorydevice an amount of the reactive gas consumed in the process chamberbased on the first concentration and the second concentrationrespectively acquired from the first gas concentration sensor and thesecond gas concentration sensor; and (c) calculate a cumulative amountof the reactive gas consumed in the process chamber by accumulating theamount of the reactive gas consumed in the process chamber calculated in(b) from a start of a supply of the process gas to the substrate in theprocess chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a vertical cross-section of a substrateprocessing apparatus according to an embodiment described herein.

FIG. 2 schematically illustrates a vertical cross-section of aprocessing furnace of the substrate processing apparatus according tothe embodiment.

FIG. 3 schematically illustrates a vertical cross-section of a vaporizerof the substrate processing apparatus according to the embodiment.

FIG. 4A schematically illustrates a vertical cross-section of a firstgas concentration meter of the substrate processing apparatus accordingto the embodiment.

FIG. 4B schematically illustrates a vertical cross-section of a secondgas concentration meter of the substrate processing apparatus accordingto the embodiment.

FIG. 5 schematically illustrates a furnace opening and surroundingsthereof of the processing furnace of the substrate processing apparatusaccording to the embodiment.

FIG. 6 schematically illustrates a configuration of a controller of thesubstrate processing apparatus and peripherals thereof according to theembodiment.

FIG. 7 is a flowchart illustrating a pre-processing performed before asubstrate processing according to the embodiment.

FIG. 8 is a flowchart illustrating the substrate processing according tothe embodiment.

EMBODIMENT

Hereinafter, an embodiment will be described with reference to FIGS. 1through 8.

(1) Configuration of Substrate Processing Apparatus

First, an example configuration of a substrate processing apparatus 10in which a method of manufacturing a semiconductor device according tothe embodiment is performed will be described with reference to FIGS. 1and 2. The substrate processing apparatus 10 is a device for processinga wafer (silicon substrate) 200 using a process gas generated byvaporizing a liquid containing hydrogen peroxide (H₂O₂) or a hydrogenperoxide solution. Preferably, the substrate processing apparatus 10 iscapable of processing the wafer 200 having a concave-convexmicrostructure such as grooves. Specifically, the microstructure refersto a structure of high aspect ratio such as narrow grooves (concavestructure) having a width of about 10 nm to 50 nm, for example.According to the embodiment, an oxide film is formed by filling thegrooves with a polysilazane film, which is a silicon-containing film,and processing the polysilazane film with a process gas. While theembodiment will be described by way of an example in which apolysilazane film is processed by a process gas, the technique describedherein is not limited to the polysilazane film. The techniques describedherein may also be applied, for example, to the treatment of filmsincluding silicon, nitrogen and hydrogen, particularly films containingsilazane bonds and plasma polymerized films of tetrasilylamine andammonia.

<Processing Vessel>

As shown in FIG. 1, a processing furnace 202 includes a processingvessel (reaction tube) 203. The processing vessel 203 is made of aheat-resistant material such as quartz and silicon carbide (SiC), and iscylindrical with an open lower end. A process chamber 201 is provided inthe hollow cylindrical portion of the processing vessel 203. The processchamber 201 is capable of accommodating wafers (substrates) 200 chargedin a boat 217, which will be described later. The boat 217 supportsconcentrically arranged in vertical direction and horizontally orientedwafers 200.

A seal cap 219, which is a furnace opening cover capable of airtightlysealing the lower end opening (furnace opening) of the processing vessel203, is provided under the processing vessel 203. The seal cap 219 isprovided under the processing vessel 203 and is in contact with thelower end of the processing vessel 203. The seal cap 219 is disk-shaped.The process chamber 201, which is a processing space where thesubstrates are processed, is defined by the processing vessel 203 andthe seal cap 219

21 Substrate Retainer>

The boat (substrate retainer) 217 supports concentrically arrangedwafers 200 in vertical direction while each of the wafers 200 are inhorizontal orientation. The boat 217 includes a plurality of supportcolumns 217 a supporting the wafers 200. The number of the supportcolumns 217 a may be three, for example. The support columns 217 a areprovided between a bottom plate 217 b and a top plate 217 c. The supportcolumns 217 a support the concentrically arranged wafers 200 in multiplestages along the axis of the processing vessel 203. The diameter of thetop plate 217 c is greater than the diameter of each of the wafers 200.

The columns 217 a, the bottom plate 217 b and the top plate 217 c aremade of base metal having good thermal conductivity such as siliconcarbide, aluminum oxide (AlO), aluminum nitride (AlN), silicon nitride(SiN) and zirconium oxide. Preferably, the columns 217 a, bottom plate217 b and top plate 217 c are made of base metal with a thermalconductivity of at least 10 W/mK. In the case where the thermalconductivity is of no importance, the columns 217 a, the bottom plate217 b and the top plate 217 c may be made of a material such as quartz.In case where the contamination of the wafer 200 by metal is of noimportance, the columns 217 a and the top plate 217 c may be made ofmetal such as stainless steel (SUS). When the columns 217 a and the topplate 217 c are made of metal, a coating such as ceramic and Teflon(registered trademark) may be formed on the surface of the columns 217 aand the top plate 217 c.

An insulating body 218 is made of a heat-resistant material such asquartz and silicon carbide, and is provided under the boat 217. Theinsulating body 218 prevents heat radiated from a first heater 207 fromreaching the seal cap 219. The insulating body 218 functions as asupport body for supporting the boat 217 aw well as an insulatingmember. As shown in FIG. 2, the insulating body 218 may be embodied by aplurality of disc-shaped insulating plates in horizontal orientation inmultiple stages. However, the insulating body 218 is not limitedthereto. For example, the insulating body 218 may be cylindrical quartzcap. The insulating body 218 may be regarded as one of the membersconstituting the boat 217.

<Elevating Mechanism>

A boat elevator (not shown) is provided under the processing vessel 203.The boat elevator is an elevating mechanism that loads the boat 217 intothe processing vessel 203 and unloads the boat 217 out of the processingvessel 203 by lifting and lowering the boat 217, respectively. When theboat 217 is elevated by the boat elevator, the seal cap 219 thenairtightly closes the furnace opening.

A rotating mechanism 267 capable of rotating the boat 217 is provided atthe seal cap 219 opposite to the process chamber 201. A rotating shaft261 of the rotating mechanism 267 is coupled to the boat 217 through theseal cap 219. As the rotating mechanism 267 rotates the boat 217, thewafers 200 are rotated.

<First Heater>

A first heater 207 is provided outside the processing vessel 203 andconcentrically arranged with the processing vessel 203. The first heater207 is capable of heating the wafers 200 accommodated in the processingvessel 203. The first heater 207 is supported by a heater base 206. Asshown in FIG. 2, the first heater 207 includes a first heating part 207a, a second heating part 207 b, a third heating part 207 c and a fourthheating part 207 d. The first heating part 207 a through the fourthheating part 207 d are provided in the processing vessel 203 along thestacking direction of the wafers 200, respectively.

A first temperature sensor 263 a, a second temperature sensor 263 b, athird temperature sensor 263 c and a fourth temperature sensors 263 dare provided between the processing vessel 203 and the boat 217,respectively. The first temperature sensor 263 a through the fourthtemperature sensor 263 d are provided for the first heating part 207 athrough the fourth heating part 207 d, respectively. The firsttemperature sensor 263 a through the fourth temperature sensor 263 dmeasures the temperature of the wafer 200 or ambient temperature, andeach of the first temperature sensor 263 a through the fourthtemperature sensor 263 d includes, for example, a thermocouple. Thefirst temperature sensor 263 a through the fourth temperature sensor 263d is capable of measuring the temperatures of wafers 200 at the centerof each of the groups of wafers 200 heated by the first heating part 207a through the fourth heating part 207 d.

The first heater 207 and the first temperature sensor 263 a through thefourth temperature sensor 263 d are electrically connected to acontroller 121 which will be described later. The controller 121controls the energization states of the first heating part 207 a throughthe fourth heating part 207 d based on the temperatures measured by thefirst temperature sensor 263 a through the fourth temperature sensor 263d such that the wafers 200 in the processing vessel 203 are at apredetermined temperature. In addition, the controller 121 is alsocapable of independently controlling the energization state or thetemperature of each of the first heating part 207 a through the fourthheating part 207 d. A first external temperature sensor 264 a, a secondexternal temperature sensor 264 b, a third external temperature sensor264 c and a fourth external temperature sensor 264 d may be furtherprovided at the first heating part 207 a through the fourth heating part207 d, respectively. The first external temperature sensor 264 a throughthe fourth external temperature sensor 264 d measures the temperaturesof the first heating part 207 a through the fourth heating part 207 d,respectively, and each of the first external temperature sensor 264 athrough the fourth external temperature sensor 264 d includes, forexample, a thermocouple. The first external temperature sensor 264 athrough the fourth external temperature sensor 264 d are connected tothe controller 121 such that the controller 121 is able to monitor thetemperature of each of the first heating part 207 a through the fourthheating part 207 d via the first external temperature sensor 264 athrough the fourth external temperature sensor 264 d.

<Gas Supply Mechanism (Gas Supply System)>

As shown in FIGS. 1 and 2, a process gas supply nozzle 501 a and anoxygen-containing gas supply nozzle 502 a are provided between theprocessing vessel 203 and the first heater 207 along the outer sidewallof the processing vessel 203. For example, the process gas supply nozzle501 a and the oxygen-containing gas supply nozzle 502 a are made ofquartz which has a low thermal conductivity. The process gas supplynozzle 501 a and the oxygen-containing gas supply nozzle 502 a may havea double wall structure. Tips (downstream ends) of the process gassupply nozzle 501 a and the oxygen-containing gas supply nozzle 502 aare inserted into the processing vessel 203 through the ceiling of theprocessing vessel 203 in airtight manner. A supply hole 501 b and asupply hole 502 b are provided at the tips of the process gas supplynozzle 501 a and the oxygen-containing gas supply nozzle 502 a locatedin the processing vessel 203, respectively. A process gas and anoxygen-containing gas are supplied into the processing vessel 203 towardthe top plate 217 c provided at the top of the boat 217 accommodated inthe processing vessel 203 through the supply hole 501 b and the supplyhole 502 b, respectively.

A gas supply pipe 602 c is connected to the upstream end of theoxygen-containing gas supply nozzle 502 a. A valve 602 a, a mass flowcontroller (MFC) 602 b which is a flow rate controller, a valve 602 dand a heater 602 e capable of heating a gas are provided at the gassupply pipe 602 c in order from the upstream side to the downstream sideof the gas supply pipe 602 c. For example, the oxygen-containing gasincludes oxygen (O₂) gas, ozone (O₃) gas, nitrous oxide (NO₂) gas andcombinations thereof In the embodiment, O₂ gas is used as theoxygen-containing gas. The heater 602 e is capable of heating theoxygen-containing gas to 80° C. to 150° C. It is preferable that theoxygen-containing gas is heated to 100° C. to 120° C. The heater 602 eassists the heating of the process gas supplied into the process chamber201 by heating the oxygen-containing gas. In addition, there-liquefaction of the process gas in the processing vessel 203 may besuppressed. Further, the oxygen-containing gas may be heated by thefirst heater 207.

Instead of the oxygen-containing gas, a gas having low reactivity withthe wafers 200 or the film formed on the wafers 200 may be suppliedthrough the oxygen-containing gas supply nozzle 502 a. For example,nitrogen (N₂) gas or rare gases such as argon (Ar) gas, helium (He) gasand neon (Ne) gas may be supplied through the oxygen-containing gassupply nozzle 502a. The process gas supply nozzle 501 a and theoxygen-containing gas supply nozzle 502 a extend along the innersidewall to the top portion of the processing vessel 203, and lower endsof the process gas supply nozzle 501 a and the oxygen-containing gassupply nozzle 502 a penetrate the lower portion of the processing vessel203 in airtight manner. At least one gas ejecting hole (gas supply hole)is provided either at the portion of the process gas supply nozzle 501 aor the portion of the oxygen-containing gas supply nozzle 502 a or bothextending along the sidewall of the processing vessel 203. The gas maybe supplied through the at least one gas ejecting hole (gas supply hole)parallel to the wafer 200.

A downstream end of a process gas supply pipe 289 a for supplying theprocess gas is connected to the upstream end of the process gas supplynozzle 501 a. A vaporizer 100, which is process gas generator capable ofgenerating the process gas by vaporizing the liquid source, a gasconcentration meter (gas concentration sensor) 500, a valve 289 b and agas port heater 285 are provided at the process gas supply pipe 289 a inorder from the upstream side to the downstream side of the process gassupply pipe 289 a. According to the embodiment, a gas containing atleast H₂O₂ gas is used as the process gas. A pipe heater (not shown)such as a jacket heater is provided around the process gas supply pipe289 a to heat the process gas supply pipe 289 a. As shown in FIG. 5, thegas port heater 285 is provided at a connecting portion between theprocess gas supply nozzle 501 a and the process gas supply pipe 289 a,and is configured to heat the process gas passing through the connectingportion. In case the process gas supply nozzle 501 a is inserted intothe processing vessel 203 through the lower portion thereof, it ispreferable that the gas port heater 285 is provided outside theprocessing vessel 203 whereat the process gas supply nozzle 501 a isinserted.

A liquid source supply system (liquid source supply mechanism) 300 forsupplying a liquid source (a liquid containing hydrogen peroxide) of theprocess gas to the vaporizer 100 and a carrier gas supply system(carrier gas supply mechanism) (not shown) are connected to thevaporizer 100.

The liquid source supply system 300 may include a liquid source supply300, a valve and a liquid mass flow controller (LMFC) 300 forcontrolling the flow rate of the liquid source supplied to the vaporizer100 provided in order from the upstream side to the downstream side ofthe liquid source supply system 300.

The carrier gas supply system may include a carrier gas supply pipe 601c, a carrier gas valve 601 a, an MFC 601 b which is a carrier gas flowrate controller and a carrier gas valve 601 d. According to theembodiment, the oxygen-containing gas such as O2 gas may be used as thecarrier gas. However, the oxygen-containing gas may include O3 gas, NOgas as well as O2 gas and combinations thereof which may be used as thecarrier gas. Further, gases having low reactivity with the wafers 200 orfilms formed on the wafers 200 may be used as the carrier gas. Forexample, nitrogen (N2) gas or rare gases such as argon (Ar) gas, helium(He) gas and neon (Ne) gas may be used as the carrier gas.

According to the embodiment, the process gas supply nozzle 501 a and thesupply hole 501 b constitute a process gas supply system. The processgas supply system may further include the process gas supply pipe 289 a,the valve 289 b, the gas concentration meter 500 and the vaporizer 100.The oxygen-containing gas supply nozzle 502 a and the supply hole 502 bconstitute an oxygen-containing gas supply system. The oxygen-containinggas supply system may further include the gas supply pipe 602 c, theheater 602 e, the valve 602 d, the MFC 602 b and the valve 602 a. Theprocess gas supply system and the oxygen-containing gas supply systemconstitute the gas supply system (gas supply mechanism).

<Vaporizer>

FIG. 3 schematically illustrates a configuration of the vaporizer 100.The vaporizer 100 vaporizes the liquid source by dropping the liquidsource onto a heated member. The vaporizer 100 includes: a vaporizervessel 101 which is the heated member, and defines a vaporizing space102; a vaporizer heater 103 for heating the vaporizer vessel 101; anoutlet port 104 for exhausting (supplying) the gas obtained byvaporizing the liquid source to the process gas supply pipe 289 a as aprocess gas; a thermocouple (temperature sensor) 105 for measuring thetemperature of the vaporizer vessel 101; a temperature controller 106for controlling the temperature of the vaporizer heater 103 based on thetemperature measured by the thermocouple 105; a dripping nozzle 107which is a liquid supply unit for supplying the hydrogen peroxidesolution supplied from the LMFC 303 into the vaporizer vessel 101; and acarrier gas inlet port 108 for supplying a carrier gas supplied throughthe carrier gas supply pipe 601 c into the vaporizer vessel 101.

The vaporizer vessel 101 is heated by the vaporizer heater 103 such thatthat the dripped liquid source is vaporized as it reaches the innersurface of the vaporizer vessel 101. A thermal insulator 109 may beprovided to improve the efficiency of the vaporizer heater 103 heatingthe vaporizer vessel 101 or to insulate the vaporizer 100 and othercomponents. In order to prevent the vaporizer vessel 101 from reactingwith the liquid source, the vaporizer vessel 101 is made of a materialsuch as quartz and SiC. The temperature of the vaporizer vessel 101 maybe lowered by the temperature or vaporization heat of the dripped liquidsource. Therefore, it is preferable that the vaporizer vessel 101 ismade of a material having a high thermal conductivity such as SiC inorder to minimize the temperature fluctuation of the vaporizer vessel101.

According to the embodiment, a liquid source which is a mixture of twoor more sources having different boiling points such as a hydrogenperoxide solution are heated and vaporized by the vaporizer 100. Evenwhen the liquid source is heated to a temperature higher than theboiling point of the liquid source, one of the one or more sourceshaving a lower boiling point may be vaporized first and the rest of theone or more sources having higher boiling points may not be vaporizedunless the liquid source is uniformly heated. As a result, theconcentration ratio among the one or more sources in the vaporized gasmay not be uniform since the rest of the one or more sources havinghigher boiling points may be concentrated in the liquid source.

More specifically, the hydrogen peroxide solution is the mixture of H₂O₂and H₂O. Therefore, the boiling point of the hydrogen peroxide solutiondepends on the concentration of H₂O₂. For example, the boiling point ofpure hydrogen peroxide (H₂O₂ concentration of 100%) is about 150° C.under atmospheric pressure, and the boiling point of a hydrogen peroxidesolution with a H₂O₂ concentration of 34% is about 106° C. underatmospheric pressure. Therefore, when the hydrogen peroxide solutionsupplied to the vaporizer vessel 101 is vaporized, the water (H₂O) inthe hydrogen peroxide solution is first vaporized unless the vaporizervessel 101 is uniformly heated. As a result, H₂O₂ may be concentrated inthe hydrogen peroxide solution.

Therefore, according to the embodiment, by rapidly heating the entirehydrogen peroxide solution on the heating surface of the vaporizervessel 100 to a temperature higher than the boiling point of thehydrogen peroxide solution having a boiling point higher than water, theconcentration of hydrogen peroxide is suppressed. More specifically, forexample, when vaporizing a hydrogen peroxide solution with a H₂O₂concentration of 34%, the vaporizer heater 103 heats the vaporizervessel 101 to a temperature higher than the boiling point of thehydrogen peroxide solution. By dripping the hydrogen peroxide solutiononto the heated surface of the vaporizer vessel 101, the droplets of thehydrogen peroxide solution are rapidly heated and vaporized at atemperature higher than 106° C. The vaporizer heater 103 is capable ofheating the vaporizer vessel 101 to a temperature higher than theboiling point of 150° C. of pure hydrogen peroxide with a H₂O₂concentration of 100% such that H₂O₂ in hydrogen peroxide solution isprevented from concentrating when vaporized.

However, the decomposition of H₂O₂ is accelerated as the heatingtemperature rises. Therefore, it is necessary for the hydrogen peroxidesolution to be heated to as low a temperature as possible while alsopreventing H₂O₂ from concentrating. In particular, H₂O₂ decomposesrapidly when the temperature exceeds 150° C. Thus, according to theembodiment, the temperature of the vaporization heater 103 is controlledto a temperature as high as the boiling point of the hydrogen peroxidesolution of a predetermined concentration, but as low as possible toprevent the concentration of H₂O₂.

<Exhaust System>

One end of a gas exhaust pipe 231 for exhausting the inner atmosphere ofthe process chamber 201 is connected to the lower sidewall of theprocessing vessel 203. A vacuum pump, which is a vacuum exhaustingdevice, is connected to the other end of the gas exhaust pipe 231 via agas concentration meter (gas concentration sensor) 600 and anAPC(Automatic Pressure Controller) valve 255 which is a pressurecontrolling device. The inner atmosphere of the process chamber 201 isexhausted by way of generating negative pressure by a vacuum pump 246.The APC valve 255 may be opened or closed to vacuum-exhausting theprocess chamber 201 or stop the vacuum exhaust. The opening degree ofthe APC valve 255 may be adjusted in order to control the inner pressureof the process chamber 201. A pressure sensor 223, which is a pressuredetector, is provided at the upstream side of the APC valve 255. Theinner pressure of the process chamber 201 may be exhausted to apredetermined pressure (vacuum level) by using above-describedcomponents. A pressure controller 224 shown in FIG. 6 is electricallyconnected to the pressure sensor 223 and the APC valve 255. The pressurecontroller 224 controls the operation of the APC valve 255 such that theinner pressure of the process chamber 201 is adjusted to a desired levelat a desired timing based on the pressure detected by the pressuresensor 223.

The gas exhaust pipe 231 and the APC valve 255 constitute the exhaustsystem. The exhaust system may further include the gas concentrationmeter 600 and the pressure sensor 223. The exhaust system may furtherinclude the vacuum pump 246.

<Gas Concentration Meter (Gas Concentration Sensor)>

The gas concentration meter 500 is provided at the process gas supplypipe 289 a. The gas concentration meter 500 measures (detects) theconcentration of the process gas flowing in the process gas supply pipe289 a supplied from the vaporizer 100. The gas concentration meter 600is provided at the gas exhaust pipe 231. The gas concentration meter 600measures (detects) the concentration of the exhaust gas flowing in thegas exhaust pipe 231 which is exhausted from the process chamber 201.Inthe embodiment, the concentrations of the gases measured by the gasconcentration meters 500 and 600 refer to the concentrations of certaingases contained in the process gas and the exhaust gas, respectively.For example, the certain gases include a reactive gas contained in theprocess gas for processing the wafers 200 such as H₂O₂ gas for oxidizingthe silicon-containing film formed on the wafers 200. That is, the gasconcentration meter 500 measures (detects) the concentration of the H₂O₂gas contained in the process gas and the gas concentration meter 600measures (detects) the concentration of the H₂O₂ gas contained in theexhaust gas.

As shown in FIG. 4A, the gas concentration meter 500 includes a cell 540through which the process gas supplied via a process gas supply pipe 289a passes; a light emitter 520 for irradiating a light beam, particularlya near-infrared ray, to the process gas passing through the cell 540; alight receiver 530 for receiving the light beam irradiated from thelight emitter 520 and passed through the process gas in the cell 540;and an analyzer (gas concentration calculator) 510 for analyzing thespectrum of the light beam received by the light receiver 530 andcalculating the concentration of H₂O₂ in the process gas. Similarly, asshown in FIG. 4A, the gas concentration meter 600 includes a cell 640through which the exhaust gas supplied via the gas exhaust pipe 231passes; a light emitter 620 for irradiating a light beam, particularly anear-infrared ray, to the exhaust gas passing through the cell 640; alight receiver 630 for receiving the light beam irradiated from thelight emitter 620 and passed through the exhaust gas in the cell 640;and an analyzer (gas concentration calculator) 610 for analyzing thespectrum of the light beam received by the light receiver 630 andcalculating the concentration of H₂O₂ in the exhaust gas. The analyzers510 and 610 are connected to the light receivers 530 and 630,respectively, via, for example, optical fibers, and analyze the spectrumof the light beam received by the light receivers 530 and 630. Theanalyzers 510 and 610 the concentrations of H₂O₂ in the process gas andexhaust gas, respectively, by evaluating the magnitudes of the uniquespectral component of the light beam passed through the process gas orexhaust gas containing the H₂O₂ in the cells 540 and 640. Theconcentration data of the H₂O₂ calculated by the analyzers 510 and 610are transmitted to the controller 121. Although the analyzers 510 and610 according to the embodiment are described as calculating theconcentration of the H₂O₂, the analyzers 510 and 610 may calculate otherdata representing the concentration of the H₂O₂ rather than theconcentration of the gas itself

<Second Heater>

When a gas containing H₂O₂ (reactive material) obtained by vaporizing ahydrogen peroxide solution (aqueous solution containing H₂O₂) or byconverting the hydrogen peroxide solution into mist state is used as theprocess gas, it is possible that the gas containing H₂O₂ is cooled downto a temperature lower than the boiling point of H₂O₂ in the processingvessel 203, resulting in the re-liquefaction of H₂O₂ or there-liquefaction of gas containing H₂O₂.

Specifically, the re-liquefaction of the gas containing H₂O₂ may occurin a region of the processing vessel 203 other than the region of theprocessing vessel 203 heated by the first heater 207. As describedabove, the first heater 207 heats the region of the processing vessel203 in which the wafer 200 is present since the first heater 207 isprovided to heat the wafer 200 in the processing vessel 203. However,the region other than where the wafer 200 is present may not beadequately heated by the first heater 207. As a result, the region otherthan the region heated by the first heater 207 may be a low temperatureregion in which the gas containing H₂O₂ may be cooled and re-liquefiedwhen passing through.

The liquid from the re-liquefaction of the gas containing the H₂O₂ mayremain at the bottom of the processing vessel 203 (the upper surface ofthe seal cap 219), which may result in a chemical reaction between theliquid and the seal cap 219 to damage the seal cap 219. The liquidremaining on the seal cap 219 may also flow out of the processing vessel203 through the furnace opening (the opening at the lower end of theprocessing vessel 203) when the seal cap 219 is lowered to open thefurnace opening of the processing vessel 203 in order to unload the boat217 from the processing vessel 203. As a result, the members around thefurnace opening of the processing furnace 202 may be also damaged andthe safety of the operator around the processing furnace 202 cannot besecured.

The liquid from the re-liquefaction of the gas containing the H₂O₂ mayhave higher H₂O₂ concentration than the hydrogen peroxide solutionsupplied into the processing vessel 203. The liquid from there-liquefaction of the gas containing the H₂O₂ may be re-vaporized inthe processing vessel 203. As described above, since the boiling pointof H₂O₂ differs from that of H₂O, and H₂O is first vaporized, the gasproduced by re-vaporization may have higher H₂O₂ concentration than thegas supplied into the processing vessel 203.

Thus, the H₂O₂ concentration of the gas produced by re-vaporization andthe concentration of the gas containing the H₂O₂ supplied into theprocessing vessel 203 may not be uniform. As a result, the substrateprocessing may not be uniform among the wafers 200 in the processingvessel 203, and the characteristics of the substrate processing maydeviate for each wafer 200. In addition, the substrate processing maydeviate for each lot of wafers 200. Moreover, as the re-liquefaction andre-vaporization of H₂O₂ are repeated, the concentration of H₂O₂ maybecome higher. As a result, the possibility of explosion or combustionmay increase.

In order to solve the above-described problems, a second heater 280 isprovided in the processing furnace 202 as shown in FIGS. 2 and 5. Thesecond heater 280 is capable of heating the region other than the regionheated by the first heater 207. That is, the second heater 280 isprovided concentric with the processing vessel 203 to surround the outerside surface (outer periphery) of the lower portion (around the furnaceopening portion) of the processing vessel 203.

The second heater 280 is capable of heating the gas containing H₂O₂,which flows from the upstream side to the downstream side of theprocessing vessel 203 toward the exhaust unit, at the lower region ofthe processing vessel 203 where the insulating body 218 is provided. Thesecond heater 280 is also capable of heating members in the lower regionof the processing vessel 203 such as the seal cap 219 for sealing thelower end opening of the processing vessel 203 and the insulating body218 provided at the bottom of the processing vessel 203. The secondheater 280 is provided lower than the bottom plate 217 b when the boat217 is loaded into the process chamber 201. The second heater 280 may beembodied by a lamp heater, for example.

The controller 121, which will be described later, is electricallyconnected to the second heater 280. The controller 121 controls theenergization state of the second heater 280 at a predetermined timingsuch that the inner temperature of the processing vessel 203 is at atemperature (e.g., 100° C. to 300° C.) high enough to suppressliquefaction of the process gas (i.e., the gas including H₂O₂). Thesecond heater 280 continues to heat the furnace opening of theprocessing vessel 203 at least during the supply of the process gas intothe processing vessel 203. Preferably, the second heater 280 continuesto heat the furnace opening of the processing vessel 203 from theloading of the wafer 200 into the processing vessel 203 until theunloading of the wafer 200 from the processing vessel 203. As a result,the re-liquefaction of the process gas at the furnace opening andattachment of particles and impurities generated in drying process,which will be described later, to the furnace opening may be prevented.By starting to heat the furnace opening by the second heater 280 afterthe wafer 200 is loaded, the time required to prepare for thepre-processing before the supply of the process gas is shortened.

As described above, the gas port heater 285 is provided at theconnecting portion between the process gas supply nozzle 501 a and theprocess gas supply pipe 289 a. The gas port heater 285 is capable ofheating the process gas passing through the connecting portion. The gasport heater 285 is controlled to be at a desired temperature such thatcondensation does not occur in the process gas supply pipe 289 a. Forexample, the gas port heater 285 is controlled to be at a temperatureranging from 50° C. to 300° C. An exhaust tube heater 284 is provided atthe connecting part between the gas exhaust pipe 231 and the processingvessel 203. The exhaust tube heater 284 is controlled to be at a desiredtemperature such that condensation does not occur in the gas exhaustpipe 231. Preferably, the exhaust tube heater 284 is controlled to be ata temperature ranging from 50° C. to 300° C.

<Controller>

As shown in FIG. 6, the controller 121, which is a control device(control means), may be embodied by a computer having a CPU (CentralProcessing Unit) 121 a, a RAM (Random Access Memory) 121 b, a memorydevice 121 c and an I/O port 121 d. The RAM 121 b, the memory device 121c and the I/O port 121 d may exchange data with the CPU 121 a via aninternal bus 121 e. An input/output device 121 such as a touch panel anda display device may be connected to the controller 121.

The memory device 121 c may be embodied by components such as flashmemory and HDD (Hard Disk Drive). A control program for controlling theoperation of the substrate processing apparatus 10 and a process recipein which information such as the order and condition of the substrateprocessing which will be described later is stored are readably storedin the memory device 121 c. The process recipe is a program that isexecuted in the controller 121 to obtain a predetermined result byperforming sequences of the substrate processing. Hereinafter, theprocess recipe and the control program are collectively referred tosimply as a program. The term “program” may refer to only the processrecipe, only the control program, or both. The RAM 121 b is a work areain which the program or the data such as the calculation data and theprocessing data read by the CPU 121 a are temporarily stored.

The I/O port 121 d is electrically connected to the components such asthe LMFC 303, the MFCs 601 b and 602 b, the valves 601 a, 601 d, 602 a,602 d, 302 and 289 b, the APC valve 255, the first heater 207 (the firstheating part 207 a through the fourth heating part 207d), the secondheater 280, the first temperature sensor 263 a through the fourthtemperature sensor 263 d, the rotating mechanism 267, the pressuresensor 223, the temperature controller 106, the gas concentration meters500 and 600, and the pipe heater (not shown).

The CPU 121 a is configured to read and execute the control programstored in the memory device 121 c, and read the process recipe stored inthe memory device 121 c in accordance with an instruction such as anoperation command inputted via the input/output device 122. The CPU 260a may be configured to control operation of the substrate processingapparatus 10 according to the process recipe. For example, the CPU 260 amay be configured to perform operation such as a flow rate adjustingoperation of the LMFC 303 for the liquid source, flow rate adjustingoperations of the MFCs 601 a and 601 b for various gases,opening/closing operations of the valves 601 a, 601 d, 602 a, 602 d, 302and 289 b, an opening/closing operation of the APC valve 255, atemperature adjusting operation of the first heater 207 based on thetemperatures measured by the first temperature sensor 263 a through thefourth temperature sensor 263 d, a temperature adjusting operation ofthe second heater 280, a start and stop of the vacuum pump 246, arotation speed adjusting operation of the boat rotating mechanism 267, atemperature adjusting operation of the vaporizer heater via thetemperature controller 106, and a temperature adjusting operation of thepipe heater. The CPU 260 a may be configured to analyze gasconcentration data obtained by the gas concentration meters 500 and 600,which will be described later.

The controller 121 may be embodied by installing the above-describedprogram stored in an external memory device 123 to a computer. Theexternal memory device 123 may include a magnetic tape, a magnetic disksuch as a flexible disk and a hard disk, an optical disk such as CD andDVD, a magneto-optical disk such as MO, and a semiconductor memory suchas a USB memory and a memory card. The memory device 121 c or theexternal memory device 123 may be embodied by a non-transitory computerreadable recording medium. Hereafter, the memory device 121 c and theexternal memory device 123 are collectively referred to as recordingmedia. Herein, “recording media” may refer to only the memory device 121c, only the external memory device 123, or both. In addition to theexternal memory device 123, a communication network such as the Internetand dedicated line may be used as the means for providing the program tothe computer.

(2) Pre-Processing

Hereinafter, the pre-processing performed before the modifying step ofthe wafer (substrate) 200 will be described with reference to FIG. 7. Asshown in FIG. 7, the pre-processing includes: a polysilazane coatingstep T20 wherein polysilazane is coated on the wafer 200; and apre-baking step T30. According to the polysilazane coating step T20, thepolysilazane is applied by a spin coater (not shown). The thickness ofthe coated polysilazane is determined by the conditions such as themolecular weight of the polysilazane, the viscosity of the polysilazanesolution and the number of revolutions of the spin coater. According tothe pre-baking step T30, the solvent is removed from the polysilazanecoated on the wafer 200. Specifically, the solvent is volatilized byheating the polysilazane coated on the wafer 200 to a temperature offrom about 70° C. to 250° C. Preferably, the polysilazane coated on thewafer 200 is heated to about 150° C.

The wafer 200 used in the pre-processing has a concave-convexmicrostructure. The applied polysilazane fills at least the grooves ofthe concave-convex structure. That is, polysilazane coating film, whichis a silicon-containing film, is formed in the grooves of the wafer(substrate) 200. Hereinafter, an example wherein a gas containing H₂O₂,which is obtained by vaporizing a hydrogen peroxide solution, is used asa process gas will be described. The silicon-containing film is a filmcontaining, for example, silicon, nitrogen and hydrogen. Thesilicon-containing film may also contain carbon or other impurities.“Microstructure” refers to a structure with a high aspect ratio such asdeep grooves or narrow grooves of about 10 nm to 30 nm formed on asilicon substrate, for example.

In the pre-processing according to the embodiment, the wafer 200 isloaded (substrate loading process, T10) into a processing apparatus (notshown) which is different from the substrate processing apparatus 10described above, and the polysilazane coating step T20 and thepre-baking step T30 are performed in the processing apparatus. The wafer200 is unloaded (substrate take-out step, T40) from the processingapparatus. However, in the pre-processing, the polysilazane coating stepT20 and the pre-baking step T30 may be performed by two separateapparatuses.

(3) Substrate Processing

Next, an exemplary sequence of the substrate processing formanufacturing a semiconductor device will be described with reference toFIG. 8. A modifying step according to the embodiment wherein asilicon-containing film formed on the wafer (substrate) 200 is modifiedinto an SiO film using a process gas containing H₂O₂ will be described.Herein, the components of the substrate processing apparatus 10 arecontrolled by the controller 121.

Since hydrogen peroxide (H₂O₂) has higher activation energy and has moreoxygen atoms in one molecule than water vapor (H₂O), hydrogen peroxide(H₂O₂) is stronger oxidant than water vapor (H₂O). Therefore, by using agas containing H₂O₂ as the process gas, the oxygen atoms can reach thefilm formed at the bottoms of the grooves of the wafer 200. As a result,the modification step may be performed more uniformly between the convexportion of the film and concave portion of the film at the bottom of thegrooves of the wafer 200. As a result, the dielectric constant of thewafer 200 after the modifying step is more uniform. Since the modifyingstep may be performed at a low temperature, problems such asdeterioration of the performance of the circuit formed on the wafer 200may be suppressed. According to the embodiment, the reactant H₂O₂vaporized or converted to be in mist state (H₂O₂ in the gaseous phase)is referred to as a “H₂O₂ gas” or a “reactive gas” and a gas containingat least H₂O₂ gas is referred to as “process gas.” An aqueous solutionof H₂O₂ is referred to as “hydrogen peroxide solution” or “liquidsource.”

<Substrate Loading Step S10>

First, a predetermined number of wafers 200 are charged into the boat217 (wafer charging). The boat 217 holding the wafers 200 is elevated bythe boat elevator and loaded into the processing vessel 203 (into theprocess chamber 201) (boat loading). With the boat 217 loaded, the sealcap 219 seals the lower end opening (furnace opening) of the processingfurnace 202.

<Pressure and Temperature Adjusting Step S20>

The vacuum pump 246 vacuum-exhausts the processing vessel 203 such thatthe inner pressure of the processing vessel 203 is adjusted to a desiredpressure (vacuum level). The oxygen-containing gas is supplied into theprocessing vessel 203 via the supply hole 501 b of the oxygen-containinggas supply system. Preferably, the oxygen-containing gas is suppliedinto the processing vessel 203 after being heated to a temperatureranging from 100° C. to 120° C. by the heater 602 e. At this time, theinner pressure of the processing vessel 203 is measured by the pressuresensor 223, and the opening degree of the APC valve 255 isfeedback-controlled based on the measured pressure (pressure adjusting).Preferably, the inner pressure of the processing vessel 203 is adjustedsuch that the processing vessel 203 is not depressurized, for example,to a pressure ranging from 700 hPa to 1,000 hPa.

The first heater 207 heats the processing vessel 203 such that thetemperature of the wafers 200 in the processing vessel 203 is adjustedto a desired first temperature ranging from 40° C. to 100° C., forexample. The energization states of the first heating part 207 a throughthe fourth heating part 207 d of the first heater 207 arefeedback-controlled based on the temperature measured by the firsttemperature sensor 263 a through the fourth temperature sensor 263 d,respectively, such that the wafers 200 in the processing vessel 203 areat the first temperature (temperature adjusting). The first heating part207 a through the fourth heating part 207 d are controlled such that thetemperatures of the first heating part 207 a through the fourth heatingpart 207 d are the same. The second heater 208 is controlled to adjustthe inner temperature of the processing vessel 203 such that the processgas is not re-liquefied in the processing vessel 203, particularly inthe lower portion of the processing vessel 203. Preferably, the secondheater 208 heats the lower portion of the processing vessel 203 to atemperature ranging from 100° C. to 200° C.

The rotating mechanism 267 starts to rotate the boat 217 and the wafers200 while the wafers 200 are heated. The rotation speed of the boat 217is controlled by the controller 121. The rotating mechanism 267continuously rotates the boat 217 until at least the modifying step S30,which will be described later, is complete.

<Modifying Step S30>

When the wafer 200 is heated to a first temperature, and the boat 217 isrotated at a predetermined speed, the liquid source (hydrogen peroxidesolution) is supplied to the vaporizer 100 by the liquid source supplysystem 300. Specifically, the flow rate of the liquid source supplied bythe liquid source supply system 300 is adjusted by the LMFC 303. Afterthe flow rate of the liquid source is adjusted, the liquid source issupplied into the vaporizer vessel 101 of the vaporizer 100 via thedripping nozzle 107 by opening the valve 302. The liquid source suppliedto the vaporizer 100 is dropped onto the inner bottom surface of thevaporizer vessel 101 through the dripping nozzle 107. Since thevaporizer vessel 101 is heated by the vaporizer heater 103 to a desiredtemperature (for example, 150° C. to 170° C.), the droplets of theliquid source (hydrogen peroxide solution) that comes in contact withthe inner bottom surface of the vaporizer vessel 101 is instantaneouslyheated and evaporated to a gas.

The process gas, which is the gas obtained from the liquid source byvaporization, is supplied to the wafers in the process chamber byopening the valve 289 b via the exhaust port 104, the process gas supplypipe 289 a, the valve 289 b, the process gas supply nozzle 501 a, andthe supply hole 501 b of the process gas supply nozzle 501 a. The H₂O₂gas contained in the process gas acts as a reactive gas. The H₂O₂ gascontained in the process gas reacts with the silicon-containing film onthe wafer to modify (oxidize) the silicon-containing film, therebyforming a SiO film.

With the process gas being supplied into the processing vessel 203, theinner atmosphere of the processing vessel 203 is exhausted by the vacuumpump 246. Specifically, the APC valve 255 is opened and the vacuum pump246 is operated, and the gas exhausted from the processing vessel 203flows through the gas exhaust pipe 231 and the gas concentration meter600. After a predetermined time has elapsed, the valve 289 b is closedand the supply of the process gas into the processing vessel 203 isstopped. After another predetermined time has elapsed, the APC valve 255is closed and the exhaust of the inner atmosphere of the processingvessel 203 is stopped.

During the supply of the process gas into the processing vessel 203, theAPC valve 255 may be closed to pressurize the processing vessel 203. Bypressurizing the processing vessel 203, the atmosphere of the processgas in the processing vessel 203 can be more uniform.

While the embodiment is described by way of an example wherein hydrogenperoxide solution is supplied to the vaporizer 100 as a liquid sourceand the process gas containing H₂O₂ is supplied into the processingvessel 203, the above-described technique is not limited thereto. Theabove-described technique may also be applied, for example, when aliquid including ozone (O₃) and a liquid such as water (H₂O) are used asa liquid source.

When the process gas is produced by the vaporizer 100 without anoxygen-containing gas supplied into the processing vessel 203, theprocessing of the wafers 200 at different locations of the boat (e.g.wafers 200 at upper portion and lower portion of the boat) may not beuniform Moreover, the amount of impurities may increase, therebydegrading the film quality. Therefore, an oxygen-containing gas may besupplied into the processing vessel 203 via the oxygen-containing gassupply nozzle 502 a and the supply port 502 b before vaporizing theliquid source into the process gas containing H₂O₂ by the vaporizer 100in order to improve process uniformity among the wafers 200 accommodatedin the processing vessel 203.

After the completion of the modifying step S30 is complete, N₂ gas(inert gas) serving as a purge gas is supplied into the processingvessel 203 while the vacuum pump 246 vacuum-exhausts the inneratmosphere of the processing vessel 203 with the APC valve 255 open.According to the embodiment, inert gas such as N₂ gas and rare gasessuch as helium (He) gas, neon (Ne) gas and argon (Ar) gas may be used asthe purge gas. The purge gas promotes the exhaust of residual processgas from the processing vessel 203.

<Drying Step S40>

After the modifying step S30 is completed, the temperature of the wafer200 is elevated to a predetermined second temperature. The secondtemperature is higher than the first temperature and is equal to orlower than the temperature of the pre-baking step T30. The secondtemperature is, for example, 150° C. After the temperature of the wafer200 is elevated to the second temperature, the wafer 200 and the insideof the processing vessel 203 are gradually dried while maintaining thesecond temperature. As a result, by-products such as ammonia, ammoniumchloride, carbon and hydrogen, which are desorbed from the polysilazanefilm, impurities such as gas from the solvent, and impurities from toH₂O₂ are prevented from reattaching to the wafer 200 while drying thewafer 200.

Preferably, the flow rate of the oxygen-containing gas may be adjustedto a second flow rate greater than the first flow rate before or whileelevating the temperature of the wafer 200 to the second temperature.The flow rate of the oxygen-containing gas ranges, for example, from 10slm to 40 slm. By adjusting the flow rate of the oxygen-containing gasas described above before or while elevating the temperature of thewafer 200 is elevated to the second temperature, the efficiency ofremoving the impurities is improved.

<Post-Baking Step S50>

After the drying step S40 is completed, the temperature of the wafer 200is elevated to a temperature higher than the second temperature of thedrying step S40 under an atmosphere containing at least one of nitrogen,oxygen and argon to remove hydrogen remaining in the SiO film. As aresult, a high quality SiO film with low hydrogen content is obtained.By performing the post-baking step S50, the SiO film with improvedquality can be obtained for a device manufacturing process requiring ahigh quality oxide film such as STI. The post-baking step S50 may beomitted in device manufacturing processes requiring a high quality oxidefilm when the manufacturing throughput is prioritized.

<Cooling and Returning to Atmospheric Pressure Step S60>

After the drying step S40 or the post-baking step S50 are completed, theparticles or impurities remaining in the processing vessel 203 areremoved by opening the APC valve 255 and exhausting the processingvessel 203. After vacuum exhaust, the APC valve 255 is closed and theinner pressure of the processing vessel 203 is returned to atmosphericpressure. Thereafter, the wafer 200 and the processing vessel 203 areheated to remove the particles and impurities still remaining after thevacuum exhaust, the gas desorbed from the wafer 200 and the residualimpurities contained in the hydrogen peroxide solution. It is preferableto the wafer 200 and the processing vessel 203 are heated underatmospheric pressure because the heat capacity of the processing vessel203 is increased and the wafer 200 and the processing vessel 203 aremore uniformly heated. After the inner pressure of the processing vessel203 is returned to atmospheric pressure and a predetermined time haselapsed, the temperature of wafer 200 is lowered until a predeterminedtemperature (e.g., a temperature at which the wafer can be unloaded) isreached.

The heating by the second heater 280 is lowered while the wafer 200 iscooled. Specifically, the electrical power supplied to the second heater280 is stopped to lower the heating by the second heater 280. Theheating by the second heater 280 is stopped while the wafer 200 iscooled to maintain the quality of the films formed on the surface of thewafers 200 uniform among the wafers 200 disposed at different locationof the boat. In addition, the adsorption of particles, impurities andthe gas generated from the wafer 200 in the processing vessel 203 aresuppressed from adsorbing to the furnace opening.

During the cooling of the wafer 200, a cooling gas supplied via acooling gas supply pipe 249 and having a flow rate thereof controlled bythe WC 251 may be supplied into a space 260 between the processingvessel 203 and the insulating member 210 and then exhausted through acooling gas exhaust pipe 253 by opening shutters 252, 254 and 256 andoperating a blower 257. N₂ gas, air, rare gas such as He gas, Ne gas andAr gas and combinations thereof may be used as the cooling gas. Thespace 260 can be rapidly cooled by supplying the cooling gas as well asthe processing vessel 203 and the first heater 207 provided in the space260. The wafer 200 in the processing vessel 203 can also be cooled in ashorter time.

Alternatively, with the shutters 254 and 256 closed, the cooling gassuch as N₂ gas may be supplied into the space 260 through the coolinggas supply pipe 249 to fill the space 260 with the cooling gas forcooling the space 260. The cooling gas in the space 260 may then beexhausted through the cooling gas exhaust pipe 253 by opening theshutters 254 and 256 and operating the blower 257.

<Substrate Unloading Step S70>

Thereafter, the seal cap 219 is lowered by the boat elevator and thelower end of the processing vessel 203 is opened. The boat 217 chargedwith the processed wafers 200 is unloaded from the processing vessel 203through the lower end of the processing vessel (boat unloading). Theprocessed wafers 200 are then discharged from the boat 217 (waferdischarging). The substrate processing according to the embodiment isnow complete.

(4) Measurement and Control of Consumption of Reactive Gas in ProcessChamber

Next, the process of measuring (calculating) the amount of the reactivegas (H₂O₂ gas according to the embodiment) consumed in the processchamber 201 using the gas concentration meters 500 and 600 will bedescribed. In the modifying step S30, the process gas containing H₂O₂gas as a reactive gas is supplied into the process chamber 201 via theprocess gas supply pipe 289 a. The gas concentration meter 500 providedin the process gas supply pipe 289 a measures the concentration of thereactive gas contained in the process gas flowing through the processgas supply pipe 289 a. Specifically, the light emitter 520 emitsnear-infrared ray to the process gas passing through the cell 540, andthe light receiver 530 receives near-infrared ray that has passedthrough the process gas. The near-infrared rays received by the lightreceiver 530 are transmitted to the analyzer 510. The analyzer 510calculates the concentration of the reactive gas in the process gaspassing through cell 540 by analyzing the spectrum of the receivednear-infrared rays and evaluating the magnitude of unique spectralcomponent of the light beam that has passed through the reactive gas inthe process gas. The spectrum can be analyzed using known generaltechniques.

In the modifying step S30, the vacuum pump 246 evacuates the inneratmosphere of the processing vessel 203. The gas concentration meter 600installed at the gas exhaust pipe 231 measures the concentration of thereactive gas contained in the exhaust gas flowing through the gasexhaust pipe 231. Specifically, the light emitter 620 emitsnear-infrared ray to the exhaust gas passing through the cell 640, andthe light receiver 630 receives near-infrared ray that has passedthrough the exhaust gas. The near-infrared rays received by the lightreceiver 630 are transmitted to the analyzer 610. Similar to theanalyzer 510, the analyzer 610 calculates the concentration of thereactive gas in the exhaust gas passing through cell 640 by analyzingthe spectrum of the received near-infrared rays and evaluating themagnitude of unique spectral component of the light beam that has passedthrough the reactive gas in the exhaust gas. The analyzer 610 analyzedthe spectrum using known general techniques similar to the analyzer 510.The data representing the concentrations (concentration data) of thereactive gas in the process gas and the reactive gas in the exhaust gasgenerated by the analyzers 510 and 610, respectively, are preferablytransmitted to the controller 121 at predetermined time intervals.

The controller 121 receives the concentration data acquired by the gasconcentration meters 500 and 600 and sequentially stores the receivedconcentration data in the components such as the storage 121 c. Thecontroller 121 may inform the user of the gas concentrations via theinput/output device 122. The controller 121 calculates the amount of thereactive gas consumed in the process chamber 201 (hereinafter, referredto as “amount of consumed reactive gas”) based on the received gasconcentration. Specifically, the controller 121 calculates thedifference between the gas concentrations obtained by the gasconcentration meters 500 and 600 as a value indicating the amount ofconsumed reactive gas. The controller 121 is also capable of furthercalculating the difference using a predetermined coefficient or usingother data acquired separately as the amount of consumed reactive gas.The calculated amount of consumed reactive gas is sequentially recordedin the components such as the storage device 121 c and is also notifiedto the user via the input/output device 122. The calculated amount ofconsumed reactive gas may be recorded and notified to reflect theprocessing speed (reaction speed) of the wafer 200.

The controller 121 is capable of storing, in the component such as thestorage 121 c, the cumulative amount of consumed reactive gas calculatedfrom the time point at which the reactive gas is first supplied to thewafer 200 in the modifying step S30, and is also capable of informingthe user of the cumulative amount of consumed reactive gas via theinput/output device 122. The cumulative amount of consumed reactive gasmay be recorded and notified to reflect the progress of the processingof the wafer 200.

While the embodiment is described by way of an example wherein thecontroller 121 calculates parameters such as the amount of consumedreactive gas. However, a dedicated calculation unit for calculating aparameter such as an amount of consumed reactive gas may be employedinstead of the controller 121. The calculation unit may be electricallyconnected to the controller 121 and can be controlled by the controller121.

One or more advantageous effects described below are provided accordingto the embodiment.

(a) The gas concentration meters 500 and 600 are provided at the processgas supply pipe 289 a for supplying the gas to the process chamber 201and the gas exhaust pipe 231 for exhausting the gas from the processchamber 201, respectively. The amount of the reactive gas consumed inthe process chamber 201 may be determined based on the concentrations ofreactive gases in the process gas and the exhaust gas measured by thegas concentration meters 500 and 600, respectively. The amount of thereactive gas participated in the chemical reaction between the reactivegas and the wafer 200 can be determined based on the amount of consumedreactive gas.

(b) Conventionally, the thickness of the film formed on the wafer 200was measured in order to determine the progress of substrate processing(e.g. the progress of the oxidation of the silicon-containing film byH₂O₂ gas). Therefore, conventionally, it was problematic that theprogress is difficult to be determined during the substrate processing,that the thickness of the film should be measured directly, and that thethickness of the film cannot be measured accurately when the thicknessof the film is thin. It can be regarded that the amount of consumedreactive gas accumulated from the time point at which the process gas isfirst supplied to the wafer 200 (the cumulative amount of consumedreactive gas) is proportional or is likely to be proportional to theprogress of the wafer processing. Therefore, by measuring the cumulativeamount of consumed reactive gas, it is possible to determine theprogress of the processing of the wafer 200 at desired time point. Bycomparing the cumulative amounts of consumed reactive gas of processinglots with one another, the processing quality can be constantly managedfor each processing lot.

(c) It can be regarded that the amount of reactive gas consumed per unittime is proportional or is likely to be proportional to the speed of theprocessing of the wafer 200 (the speed of the oxidation of thesilicon-containing film by H₂O₂ gas according to the embodiment).Therefore, the speed of the processing of the wafer 200 can bedetermined by measuring the amount of consumed reactive gas per unittime. The processing quality can be maintained for each processing lotby comparing the amount of the reactive gas consumed per unit time orthe change thereof among the processing lots.

(d) The amount of consumed reactive gas generally increases or decreasesdepending on the number of wafers 200 processed in the processing vessel203. According to the embodiment, it is possible to determine the amountof consumed reactive gas (the amount of consumed reactive gas per unittime and the history data thereof) per batch of wafers 200 in eachprocessing lot. Therefore, conditions such as the supplied amount of theprocess gas can be optimized according to the number of wafers 200.

According to the embodiment, the examples of processing described beloware performed based on the calculated amount of consumed reactive gas.

<First Example of Processing>

As described above, since the speed of the processing of the wafer 200can be determined by measuring the amount of consumed reactive gas perunit time, the speed of the processing of the wafer 200 can befeedback-controlled based on the measured amount of consumed reactivegas. The amount of the process gas produced by the vaporizer 100 may beadjusted by controlling the LMFC 303 and the MFC 601 b based on thecalculated amount of consumed reactive gas per unit time, therebycontrolling the flow rate of the process gas supplied into the processchamber 201. As a result, the speed of the processing of the wafer 200can be controlled. Specifically, when the amount of consumed reactivegas per unit time is determined to be lower than a predetermined value,the flow rate of the process gas may be increased. Similarly, when theamount of consumed reactive gas per unit time is determined to be higherthan the predetermined value, the flow rate of the process gas may bedecreased.

<Second Example of Processing>

When the amount of consumed reactive gas per unit time decreases to apredetermined level, it can be regarded that the chemical reactionoccurring at the wafer 200 (the reaction of oxidizing thesilicon-containing film by the H₂O₂ according to the embodiment) issaturated, and the modifying step can be terminated. As a result, theprocessing time can be shortened and the throughput can be improved bystopping the supply of the process gas.

<Third Example of Processing>

As described above, by measuring the cumulative amount of consumedreactive gas, the progress of the processing of the wafer 200 at eachtime point of substrate processing can be determined. According to thethird example of processing, when the cumulative amount of consumedreactive gas reaches a predetermined level, the modifying step isterminated. As a result, the processing time can be shortened and thethroughput can be improved.

<Fourth Example of Processing>

When the amount of consumed reactive gas per unit time is determined tobe either lower than or higher than a predetermined value, an alarm maybe issued via components such as the input/output device 122 to informthe user of possible fault in the processing of wafers in the processchamber 201.

<Fifth Example of Processing>

When the cumulative amount of consumed reactive gas is determined to beeither lower than or higher than a predetermined value at the end of themodifying step, an alarm may be issued via components such as theinput/output device 122 to inform the user of possible fault in theprocessing of a processing lot.

<Sixth Example of Processing>

Generally, the amount of consumed reactive gas generally increases ordecreases depending on the number of wafers 200 processed in theprocessing vessel 203. According to the sixth example of processing, anoptimal amount of the process gas may be determined per batch of wafers200 in each processing lot. Specifically, the controller 121 records(logs) the history of the amount of consumed reactive gas per unit timefor each processing lot in the component such as the storage device 121c. The controller 121 acquires the number of wafers 200 to be processedin the processing vessel 203 for each processing lot via theinput/output device 122 or from the external memory device 123.Subsequently, the controller 121 associates the amount of consumedreactive gas per unit time with the number of the wafers 200 for eachprocessing lot. As a result, the history data (pattern) of the amount ofconsumed reactive gas per unit time with respect to the number of wafers200 can be obtained. The controller 121 optimizes the amount of suppliedprocess gas by adjusting the amount of the process gas based on thehistory data of the amount of consumed reactive gas per unit timeassociated with the number of the wafers 200. The controller 121 refersto the history data of the amount of consumed reactive gas of theprevious process lot having the same number of wafers 200, and controlsthe amount of the supplied process gas such that the amount of thesupplied process gas is no less than that of the process in the historydata. As a result, under-supply of the process gas can be prevented aswell as over-supply of the process gas.

<Seventh Example of Processing>

When the difference between the history data (pattern) of the reactivegas consumption per unit time of current processing lot and the historydata (pattern) of the reactive gas consumption per unit time of theprevious processing lot of the same number of wafers 200 is out of apredetermined range, an alarm may be issued via components such as theinput/output device 122 to inform the user of possible fault in theprocessing of wafers in the process chamber 201.

Other Embodiments

While the technique is described in detail by way of the embodiment andexamples, the above-described technique is not limited thereto. Theabove-described technique may be modified in various ways withoutdeparting from the gist thereof

For example, according to the above-described embodiments, a gascontaining H₂O₂ gas is used as the process gas. However, theabove-described technique is not limited thereto. That is, the processgas may be a gas produced from vaporizing a solution of a solid source(reactant) or a liquid source (reactant) dissolved in a solvent at roomtemperature (reactant dissolved liquid). When the boiling point of thesource differs from that of the solvent, the above-describedadvantageous effects can be easily obtained. In addition, theabove-described technique is not limited to the case where theconcentration of the source increases when the process gas isre-liquefied. The above-described technique may be applied to a casewhere the concentration of the source decreases when the process gas isre-liquefied. According to the above-described technique, the processgas having uniform concentrated in the processing vessel 203 may beobtained even when the concentration of the source decreases due tore-liquefaction.

For example, according to the above-described embodiments, hydrogenperoxide gas is used as the process gas. However, the above-describedtechnique is not limited thereto. H₂O gas produced by the reaction of agas containing hydrogen (hydrogen-containing gas) such as hydrogen (H₂)gas and a gas containing oxygen (oxygen-containing gas) such as oxygen(O)) gas. Water vapor generated by heating water may also be used as theprocess gas.

For example, according to the above-described embodiments, the processgas is produced by heating and vaporizing a liquid source. However, theabove-described technique is not limited thereto. The above-describedtechnique may be applied when processing a substrate in a processchamber by supplying a process gas containing a predetermined reactivegas into the process chamber.

The H₂O₂ contained in the process gas described above may be H₂O₂molecules or a cluster of H₂O₂ molecules. When hydrogen peroxidesolution is used to generate a gas containing H₂O₂, H₂O₂ molecules orthe cluster of H₂O₂ molecules may be separated from the hydrogenperoxide solution. H₂O₂ may be in a mist state in which the clusters arecombined.

When a gas (water vapor) produced by vaporizing water (liquid source) isused as the process gas, the water vapor supplied to the wafer 200 maybe H₂O molecules or a cluster of H₂O molecules. When water is convertedwater from a liquid phase to a gaseous phase, H₂O molecules or thecluster of H₂O molecules may be separated. H₂O may be in a mist state inwhich the clusters are combined.

While the embodiment is described by way of an example wherein the waferhaving the polysilazane film is processed, the above-described techniqueis not limited thereto. The above-described technique may also beapplied when a wafer having thereon a film containing a silazane bond(—Si—N—). The above-described technique may also be applied when acoating film including materials such as hexamethyldisilazane (HMDS),hexamethylcyclotrisilazane (HMCTS), polycarbosilazane andpolyorganosilazane.

While the embodiment is described by way of an example wherein the waferhaving thereon a spin-coated and prebaked film containing a silazanebond is processed, the above-described technique is not limited thereto.The above-described technique may also be applied when oxidizingnon-prebaked silicon-containing film formed by CVD method from siliconsources such as monosilane (SiH₄) gas and trisilylamine (TSA) gas.Particularly, the non-prebaked silicon-containing film may be formed byflowable CVD which enables the filling of grooves with high aspect ratiowith the silicon-containing film. The silicon-containing film in thegrooves may be subjected to oxidation process or annealing processaccording to the above-described technique.

According to the above-described embodiments, the substrate processingusing a substrate processing apparatus having vertical type processingfurnace is exemplified. However, the above-described technique is notlimited thereto. The above-described technique may also be applied tothe substrate processing using a single type substrate processingapparatus, a substrate processing apparatus having hot wall typeprocessing furnace, a substrate processing apparatus having cold walltype processing furnace and a substrate processing apparatus capable ofprocessing the wafers 200 by activating the process gas.

While the embodiment is described by way of an example wherein theconcentration of the H₂O₂ gas is acquired by the gas concentration meteraccording to the analysis described above, the above-described techniqueis not limited thereto. The above-described technique may also beapplied when the concentration of the H₂O₂ gas is acquired according toother well-known analyses and the same advantageous effects areobtained.

According to the technique described herein, the progress of thereaction between the substrate and the reactive gas contained in theprocess gas in the process chamber can be acquired, monitored andrecorded during the substrate processing.

What is claimed is:
 1. A substrate processing apparatus comprising: aprocess chamber accommodating a substrate; a process gas supply systemconfigured to supply a process gas into the process chamber via aprocess gas supply pipe; an exhaust pipe configured to exhaust an inneratmosphere of the process chamber; a first gas concentration sensorconfigured to detect a first concentration of a reactive gas containedin the process gas in the process gas supply pipe; a second gasconcentration sensor configured to detect a second concentration of thereactive gas contained in an exhaust gas in the exhaust pipe; and acontroller configured to: (a) control the process gas supply system tosupply the process gas to the substrate in the process chamber; (b)acquire the first concentration detected by the first gas concentrationsensor and the second concentration detected by the second gasconcentration sensor at predetermined time interval, and calculate andrecord in a memory device an amount of the reactive gas consumed in theprocess chamber based on the first concentration and the secondconcentration respectively acquired from the first gas concentrationsensor and the second gas concentration sensor; and (c) calculate acumulative amount of the reactive gas consumed in the process chamber byaccumulating the amount of the reactive gas consumed in the processchamber calculated in (b) from a start of a supply of the process gas tothe substrate in the process chamber.
 2. The substrate processingapparatus of claim 1, further comprising a valve provided at the processgas supply pipe, wherein the controller is further configured to controlthe valve to start the supply of the process gas to the substrate in theprocess chamber by opening the valve.
 3. The substrate processingapparatus of claim 1, wherein the controller is configured to calculatethe amount of the reactive gas consumed in the process chamber based ona difference between the first concentration and the secondconcentration in (b).
 4. The substrate processing apparatus of claim 1,further comprising an input/output device, wherein the controller isfurther configured to control the input/output device to inform a userof the cumulative amount calculated in (c).
 5. The substrate processingapparatus of claim 4, wherein the controller is further configured tocontrol the input/output device to inform the user of the cumulativeamount calculated in (c) as a progress of processing of the substrate.6. The substrate processing apparatus of claim 1, wherein the controlleris further configured to control the process gas supply system to stopthe supply of the process gas to the substrate in the process chamberwhen the cumulative amount calculated in (c) reaches a predeterminedvalue.
 7. The substrate processing apparatus of claim 1, wherein thecontroller is further configured to record the cumulative amountcalculated in (c) in the memory device.
 8. The substrate processingapparatus of claim 1, further comprising a process gas generatorconfigured to generate and supply the process gas containing thereactive gas including hydrogen peroxide to the process gas supply pipe.9. The substrate processing apparatus of claim 1, further comprising avaporizer configured to vaporize hydrogen peroxide solution to producethe process gas and supply the process gas to the process gas supplypipe.
 10. The substrate processing apparatus of claim 1, wherein thefirst gas concentration sensor comprises: a cell wherethrough theprocess gas passes; a light emitter configured to irradiate anear-infrared ray to the process gas passing through the cell; a lightreceiver configured to receive the near-infrared ray irradiated to theprocess gas; and a calculator configured to calculate the firstconcentration based on a spectrum of the near-infrared ray received bythe light receiver.